1. Technical Field
The present invention relates to a method and a structure for mounting a sensor substrate of a brushless motor. More specifically, the present invention relates to a brushless motor provided with a position detection element such as a Hall integrated circuit (IC), and particularly relates to a method and a structure for mounting a printed board, i.e., a sensor substrate, provided with a position detection element to shorten the dimension in the axial direction, on an inner diameter side of a coil end.
2. Background Art
A brushless motor generally includes a rotor provided with a permanent magnet and a rotational position detection element, such as a Hall IC, for detecting magnetic pole positions of the permanent magnet of the rotor, which is provided on the side of a stator. In recent years, it has been more and more highly demanded by the market to reduce the size and the thickness of a motor, and this also applies to a brushless motor. In reducing the thickness of a brushless motor, the position and the method of arrangement of a rotational position detection element such as a Hall IC and the degree of the fixing strength are the important factors. In the inventions of Patent Literatures 1 and 2, a printed board on which a rotation detection element is provided is arranged so that it is mounted on a coil end of stator winding, and accordingly, the rotation detection element may be distant from the permanent magnet of the rotor, which may cause problems in the detection of the magnetic poles. Patent Literatures 1 and 2 attempt to solve the problem by using a permanent magnet and a magnetic portion of the rotor that are long in the axial direction. Patent Literature 3 discloses a method for fixing a printed board. In Patent Literature 3, pins constituted by a thermoplastic material are allowed to pass through holes formed through a printed board, and then the printed board is fixed by thermally deforming the tips of the pins by using a jig.